kill(2) [mojave man page]
KILL(2) BSD System Calls Manual KILL(2) NAME
kill -- send signal to a process SYNOPSIS
#include <signal.h> int kill(pid_t pid, int sig); DESCRIPTION
The kill() function sends the signal specified by sig to pid, a process or a group of processes. Typically, Sig will be one of the signals specified in sigaction(2). A value of 0, however, will cause error checking to be performed (with no signal being sent). This can be used to check the validity of pid. For a process to have permission to send a signal to a process designated by pid, the real or effective user ID of the receiving process must match that of the sending process or the user must have appropriate privileges (such as given by a set-user-ID program or the user is the super-user). A single exception is the signal SIGCONT, which may always be sent to any descendant of the current process. If pid is greater than zero: Sig is sent to the process whose ID is equal to pid. If pid is zero: Sig is sent to all processes whose group ID is equal to the process group ID of the sender, and for which the process has permission; this is a variant of killpg(2). If pid is -1: If the user has super-user privileges, the signal is sent to all processes excluding system processes and the process sending the signal. If the user is not the super user, the signal is sent to all processes with the same uid as the user, excluding the process sending the signal. No error is returned if any process could be signaled. For compatibility with System V, if the process number is negative but not -1, the signal is sent to all processes whose process group ID is equal to the absolute value of the process number. This is a variant of killpg(2). RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
kill() will fail and no signal will be sent if: [EINVAL] Sig is not a valid, supported signal number. [EPERM] The sending process is not the super-user and its effective user id does not match the effective user-id of the receiving process. When signaling a process group, this error is returned if any members of the group could not be signaled. [ESRCH] No process or process group can be found corresponding to that specified by pid. [ESRCH] The process id was given as 0, but the sending process does not have a process group. SEE ALSO
getpgrp(2), getpid(2), killpg(2), sigaction(2) STANDARDS
The kill() function is expected to conform to IEEE Std 1003.1-1988 (``POSIX.1''). 4th Berkeley Distribution April 19, 1994 4th Berkeley Distribution
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kill(2) System Calls kill(2) NAME
kill - send a signal to a process or a group of processes SYNOPSIS
#include <sys/types.h> #include <signal.h> int kill(pid_t pid, int sig); DESCRIPTION
The kill() function sends a signal to a process or a group of processes. The process or group of processes to which the signal is to be sent is specified by pid. The signal that is to be sent is specified by sig and is either one from the list given in signal (see sig- nal.h(3HEAD)), or 0. If sig is 0 (the null signal), error checking is performed but no signal is actually sent. This can be used to check the validity of pid. The real or effective user ID of the sending process must match the real or saved (from one of functions in the exec(2) family) user ID of the receiving process, unless the privilege {PRIV_PROC_OWNER} is asserted in the effective set of the sending process (see intro(2)), or sig is SIGCONT and the sending process has the same session ID as the receiving process. A process needs the basic privilege {PRIV_PROC_SESSION} to send signals to a process with a different session ID. See privileges(5). If pid is greater than 0, sig will be sent to the process whose process ID is equal to pid. If pid is negative but not (pid_t)-1, sig will be sent to all processes whose process group ID is equal to the absolute value of pid and for which the process has permission to send a signal. If pid is 0, sig will be sent to all processes excluding special processes (see intro(2)) whose process group ID is equal to the process group ID of the sender. If pid is (pid_t)-1 and the {PRIV_PROC_OWNER} privilege is not asserted in the effective set of the sending process, sig will be sent to all processes excluding special processes whose real user ID is equal to the effective user ID of the sender. If pid is (pid_t)-1 and the {PRIV_PROC_OWNER} privilege is asserted in the effective set of the sending process, sig will be sent to all processes excluding special processes. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned, no signal is sent, and errno is set to indicate the error. ERRORS
The kill() function will fail if: EINVAL The sig argument is not a valid signal number. EPERM The sig argument is SIGKILL and the pid argument is (pid_t)-1 (that is, the calling process does not have permission to send the signal to any of the processes specified by pid). The effective user of the calling process does not match the real or saved user and the calling process does not have the {PRIV_PROC_OWNER} privilege asserted in the effective set, and the calling process either is not sending SIGCONT to a process that shares the same session ID or does not have the {PRIV_PROC_SESSION} privilege asserted and is trying to send a signal to a process with a different session ID. ESRCH No process or process group can be found corresponding to that specified by pid. USAGE
The sigsend(2) function provides a more versatile way to send signals to processes. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |Async-Signal-Safe | +-----------------------------+-----------------------------+ SEE ALSO
kill(1), intro(2), exec(2), getpid(2), getsid(2), setpgrp(2), sigaction(2), sigsend(2), signal(3C), signal.h(3HEAD), attributes(5), privi- leges(5), standards(5) SunOS 5.10 22 Mar 2004 kill(2)